I thought I would also add the following: I read on another Mercedes board that the pulley and balancer can come loose if they are installed incorrectly. It is my understanding that these two parts can rotate as you crank down on the bolt, which damages the key rihgt then and there, with the result that everything comes loose again in the near future. What you are supposed to do is install them a little off to the left, so that when you tighten the bolt they rotate slightly to the right and fall into place with the key and slotj. Otherwise the pulley and balancer try to rotate and end up putting a lot of stress on the keys. In any event, you have to watch as you tighten to makesure the balancer isn't turning (and in turn damaging the key) as you are tightening the bolt.

Someone please correct me if I explained this wrong. I just remember reading something about this a long time ago and wanted to make the point as best I could. I have never actually done this job, so I can't give any other advice besides hearsay.

Good luck.

Greg
'84 300D